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packages/unittest/lib/src/matcher/expect.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library unittest.matcher.expect;
 
 import 'core_matchers.dart';
 import 'description.dart';
 import 'interfaces.dart';
 import 'util.dart';
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 /// [formatter] is a reference to the new formatter; if this is omitted or
 /// null then the failure formatter is reset to the default. The new
 /// formatter is returned; this allows custom expect handlers to easily
 /// get a reference to the default formatter.
 ErrorFormatter configureExpectFormatter([ErrorFormatter formatter = null]) {
   if (formatter == null) {
     formatter = _defaultErrorFormatter;
   }
   return _assertErrorFormatter = formatter;
 }